This application is based on and claim priority under 35 U.S.C. xc2xa7119 with respect to Japanese Application NO. 2001-160471 filed on May 29, 2001, the entire content of which is incorporated herein by reference.
This invention generally relates to a torque transmission device. More particularly, the present invention pertains to a torque transmission device which is applied as an operational force transmission mechanism of a window regulator and a height adjustment device of a vehicle seat, in which an output shaft can be rotated for transmitting the rotation from the operation side to the device and the output shaft cannot be rotated from the device side.
A known torque transmission device for achieving foregoing characteristics is disclosed in U.S. Pat. No. 5,460,253. The known torque transmission device according to the U.S. Pat. No. 5,460,253 includes an inside ring connected to a fixed member, an outside ring positioned keeping a clearance from the inside ring, two pairs of rollers positioned in the clearances between the outside ring and the inside ring, a spring positioned between the pair of rollers for increasing the distance between the rollers, a pawl portion inserted from a hole provided on a side wall of the outside ring for sandwiching the pair of rollers from the different side from the spring, an operation lever rotatably supported on a circumference of the inside ring, and a shaft fixed to the outside ring and positioned to be penetrated into a bore of the inside ring. The clearance between the inside ring and the outside ring includes a gradually narrowed portion. The spring provided between the pair of rollers pushes each roller towards the narrowed clearance. According to the torque transmission device with this construction, the large load is generated between the rollers and the inside ring and the outside ring by the wedge effect to obtain the large frictional force accompanied with the load. Thus, the relative rotation between the inside ring and the outside ring is checked strongly. When the torque transmission device with the foregoing construction is assembled to an application device for providing the rotational torque, a stress on the shaft of the torque transmission device is caused by a gear of the application device. The rotational torque is transmitted from the shaft to the outside ring, notwithstanding, the shaft is not rotated because the relative rotation between the outside ring, the roller, and the inside ring is strongly checked and the inside ring is connected to the fixed member.
On the other hand, when the operational lever is operated, the pawl portion displaces the roller to be released from the condition sandwiched in the clearance between the inside ring and the outside ring against the biasing force of the spring. The operational lever also has a construction for rotating the shaft with lighter operational force by rotating the outside ring by the contact between the pawl portion and the hole on the outside ring side wall.
According to the foregoing known torque transmission device with the construction for locking the outside ring and the inside ring by sandwiching the roller in the clearance between the outside ring and the inside ring, the respective rings and the roller are in line contact each other when the torque is transmitted from the outside ring to the inside ring via the roller. The large stress is generated because the load is concentrated on the contacted line portion. In addition, because the inside ring, the outside ring and the roller under operation contact each other at approximately the same position on every checking operations, the wear-out of the inside ring and the outside ring is increased.
A need thus exists for a torque transmission device which does not cause the concentration of the load applied to the inside ring and the outside ring and achieves high durability.
According to one aspect, A torque transmission device comprises an inside support member having a first contact surface portion positioned on an outer periphery of the inside support member, an outside support member having a second contact surface portion positioned on an inner periphery of the outside support member, a first holding portion in which a clearance between the first contact surface portion and the second contact surface portion is gradually decreased in one peripheral direction, a second holding portion in which a clearance between the first contact surface portion and the second contact surface portion is gradually decreased in the other peripheral direction, a pair of interposition members which is supported on the first holding portion and the second holding portion respectively, an elastic member positioned between the pair of interposition members for biasing each interposition member in a direction in which the each clearance of the first and the second holding portion is decreased, an operation member for moving one of the pair of interposition members in a direction for increasing the clearance of the first or the second holding portion against a biasing force of the elastic member.
Each interposition member comprises a third contact surface portion being in surface contact with the first contact surface portion and a fourth contact surface portion being in surface contact with the second contact surface portion.
According to another aspect, a torque transmission device comprises an inside support member having a first contact surface portion positioned on an outer periphery of the inside support member, an outside support member having a second contact surface portion positioned on an inner periphery of the outside support member, a first holding portion in which a clearance between the first contact surface portion and the second contact surface portion is gradually decreased in one peripheral direction, a second holding portion in which a clearance between the first contact surface portion and the second contact surface portion is gradually decreased in the other peripheral direction, a pair of interposition members which is supported on the first holding portion and the second holding portion respectively, an elastic member positioned between the pair of interposition members for biasing each interposition member to a direction in which the each clearances of the first holding portion and the second holding portion is,decreased, an operation member for moving, one of the pair of interposition members to a direction in which the clearance of the first or the second holding portion is increased against a biasing force of the elastic member, a gear formed on the inside support member for transmitting an operational force to an external device, a shaft inserted through the inside support member, the operation member, the outside support member, and an operation handle, for transmitting the operational force from the operational handle to the external device.
Each interposition member comprises a third contact surface portion being in surface contact with the first contact surface portion and a fourth contact surface portion being in surface contact with the second contact surface portion.
According to further aspect, a torque transmission device comprises an inside support member having a first contact surface portion positioned on an outer periphery of the inside support member, an outside support member having a second contact surface portion positioned on an inner periphery of the outside support member, a first inclined surface provided on the inside support member, the first inclined surface gradually increasing a height in one peripheral direction, a second inclined surface provided on the inside support member, the second inclined surface gradually increasing a height in the other peripheral direction, a pair of interposition members which are disposed on the first inclined surface and the second inclined surface, an elastic member positioned between the pair of interposition members for biasing each interposition member to a direction in which each clearances between the inside support member and the outside support member at the first and the second inclined surface is decreased, an operation member for moving one of the paired interposition members to a direction in which the clearance between the inside support member and the outside support member at the first and the second inclined surface is increased selectively against a biasing force of the elastic member, a gear formed on the inside support member for transmitting an operational force to an external device, a shaft inserted through the inside support member, the operation member, the outside support member, and an operation handle, for transmitting the operational force from the operational handle to the external device.
Each interposition member comprises a third contact surface portion being in surface contact with the first contact surface portion and a fourth contact surface portion being in surface contact with the second contact surface portion.